Homegrown terrorists are U.S. citizens who become radicals with the intent of killing Americans.
An act of violence brought Daris Long and Melvin Bledsoe together. They say their lives were shattered, and they want to warn others.
Pvt. Andy Long and Carlos Bledsoe never knew each other until June 1, 2009.
By the time Carlos Bledsoe changed his name to Abdul Hakim Mohammed, he'd already left Tennessee State University to study with al-Qaeda in Yemen.
Mohammed shot and killed Pvt. Long three years ago, outside an army recruiting office in Little Rock, Arkansas.
He's now serving life in prison.
"This is a story that needs to get out. It's here," Long said. "Melvin didn't raise his son to kill my son."
A new documentary entitled "Losing Our Sons" features Long and Bledsoe. The documentary says Islamic radicals recruited Bledsoe's son on his college campus.
The fathers believe it's happening at universities all over the country.
"Radical Islam came into my house, stole my son," Bledsoe said. "The American people and the American government is in the denial that it's not happening."
Metro State University Political Science Professor Dr. Norman Provizer says the facts don't point a widespread problem.
"Be careful of over reacting," Provizer said. "The notion that there is a cauldron brewing, producing all of these radical terrorists just doesn't seem to coincide with reality."
Director of the Center for Middle East Studies at DU, Dr. Nader Hashemi, says claims of terrorists canvassing campuses are fueled by what he calls Islamaphobia.
"It's similar to anti-semitism. It's similar to anti-black racism. It's a claim that somehow Muslims and Islam are a threat," Hashemi said.
Former State Department Special Agent Fred Burton orchestrated the arrest of the World Trade Center bomber. Burton is now vice president of Stratfor, a private global intelligence firm in Austin, Texas.
Burton says it's more common now for terrorists to leave the U.S. and become radicalized in other countries.
"Transition back into the United States for the purposes of carrying out terrorist attacks," Burton said.
Burton cautions the problem, while real, is relatively small considering there are millions of students on campuses nationwide.
"You need to put things in perspective," Burton said.
While Islam took center stage after 9/11, Oklahoma City bomber Timothy McVeigh was a Christian extremist.
Long and Bledsoe liken Mohammed's crime to the deadly attack on Fort Hood, Texas carried out by a Virginia-born doctor who turned to extremism, Nidal Hasan.
Hasan killed 13 people.
"The fact of the matter is, people are dying," Long said.
Long and Bledsoe spoke at Colorado Christian University and say they are on a mission to expose what they believe is an epidemic of homegrown terrorism.
"It should never happen to any other American citizen. And I want to let the world know," Bledsoe said.